Scenario Set up
Type of Feedback Mechanism
Receptor Apparatus
Control
Effector
Extra Objectives
Guiding Questions
What is the order of response to Ben's drop in blood pressure?
A) The nervous system senses the drop in blood pressure.
B) The nervous system stimulates part of the body to increase blood pressure.
C) The heart increases the rate of pumping.
D) The nervous system senses the increase in blood pressure and the heart is signaled to stop beating as quickly.
These events are an example of the processes involved in a negative feed back system: the human body attempts to eliminate the “lowness” of the blood pressure. The receptor apparatus is the hypothalamus in the brain. The control is the heart. The effector is in a sense a further feed back system - the brain continues to signal the heart to change the blood pressure by beating more quickly or less quickly.
What does the term blood pressure describe?
The term blood pressure describes the pressure exerted by blood on the walls of blood vessels.
List specific examples of thermoregulation that you observed on this campus last Friday.
People shivering - a response to being cold.
People quickly traveling outdoors (not staying outside for long periods of time). This is an example of homeostatic behavior. (It is likely that people had further motives to move indoors.)
People selecting heavy pieces of clothing that retain heat in order to prevent heat loss. Again, this is an example of homeostatic behavior.
The hair on cats was tending to be very close to their bodies.
Why would a oral temperature be a more accurate reading than an axillary ,under the armpit, temperature reading?
Oral temperature is taken directly from the mouth which is an internal component of the body (with an external opening). Outside of the body there is a layer of skin. This layer of skin has mechanisms that assist in the process of cooling down the body or warming the body depending on the need of the moment. The mouth is not designed for that purpose. The mouth is also closely related to the digestive system, sensory system, and others - making it a prime target for more accurate temperature readings.
What are the components of the pH equilibria?
The components of any given pH equilibrium are hydronium and hydrogen ions. The pH equilibrium is present when there is an equal amount of hydronium ions as hydrogen ions.
How does the respiratory system affect pH balance?
The respiratory system's major function is that of gas exchange in and out of the organism. In the human body this is mostly conceptualized by the lungs: taking in oxygen and exporting carbon-dioxide. When the carbon-dioxide (CO-2) is released it is carrying some of the ions (either hydronium or hydrogen ions) that play a role in the equilibrium of pH in the blood stream of the human body. The respiratory system can be said to “throw off” pH balance.
In what other ways could you affect the osmolarity of your blood?
Increase/decrease salt intake.
Increase/decrease time spent on activities which “take” salt.
How do LH, ADH, and TSH affect blood osmolarity?
ADH is released by the hypothalamus as a method of control to reduce high blood osmolarity levels. Secretion of TRH and TSH are inhibited by high blood levels of thyroid hormones.
Of the two kidney choices, which did you choose first and what reasoning did you use to make your choice?
I chose the second option first. The second option involved the term ADH. ADH was said to have been released into the system to trigger the kidney.
How many guesses did you use before you got the correct receptor sequence for glucose inbalance?
2 guesses were used before the pancreas was chosen.
What's the connection between glucose and insulin?
Glucose-levels are sensed by the pancreas and insulin is then released to tell other cells throughout the body to take up glucose to correct the glucose imbalance.
Compare and contrast the brain's response to changing glucose levels of the other body parts listed.
The brain responds to stress by requesting an increase in glucose. When there is too much glucose the pancreas recognizes this (without the help of the nervous system) and releases insulin. Insulin is a hormone that is like a messenger. Other cells in the body receive the message and take in glucose.
In comparison to temperature regulation the brain has limited control over blood-glucose levels. It seems as if the brain is not able to directly decrease glucose levels and instead relies on the pancreas's continued operation to do so. The hypothalamus monitors blood pressure and releases hormones to change the pressure. This is different from the way that glucose levels are maintained. This lack of conformity in the function of the systems throughout the human body goes to show that evolution is not a goal-directed process.
Work through the rest of the simulation and devise a series of at least 10 thought questions that you would want the students in the other PRE-AP AH class to answer as proof of their learning efforts.
How does the central nervous system notify other organs/systems to do something?
How is diffusion related to homeostatic processes?
How does the hypothalamus sense a change in temperature?
When Ben's body becomes cold the brain is stimulated to initiate change. This change then is carried out by muscles. This is seen in the behavior of shivering - rapid contractions of the muscles. By shivering more heat is generated as a product of metabolism.
When Ben's body starts active movement - sprinting - his muscles start to feel “like they're giving out”. Ben's muscles produced a chemical that lowered the pH level of his blood. The nervous system sees this and stimulates some changes. For example, the lungs can remove carbon-dioxide from the body. Through the removal of carbon-dioxide, excess H+ ions are removed from the system and thus raising the pH of the blood. The lungs shifted the “bicarbonate buffer equilibrium”.
Ben's brain interprets a level of stress. It sees the need to increase the level of glucose in the system (especially in the region of the neocortex). The pancreas is stimulated to release a hormone. This hormone then is intercepted by other organs to provide the additional glucose requested. The adrenal gland also releases hormones to the other portions of the body. The liver is directly stimulated by the nervous system to release glucose.
Ben increases the concentration of salt in his blood system. The nervous system is stimulated and transfers responsibility to the pituitary gland. This gland releases a special hormone - the antiduretic hormone - into the blood. The kidney is stimulated by this hormone. The kidney increases the volume of water in Ben's blood. Blood osmolarity is thus lowered.
The blood sugar has increased (due to drinking soda). The pancreas increases the insulin hormone into the blood. Insulin triggers the cells of the pituitary gland to take up glucose from Ben's blood. The liver is triggered to do the same. The adrenal gland the same. Kidney the same. The muscles the same., The lungs too. Then the heart and the nervous system.
Bryan Bishop Ben's Bad Day February 23rd, 02006